1. Field of the Invention
The invention relates to a coupling device, and more particularly to a coupling device with improved isolation.
2. Description of the Related Art
FIG. 1 shows a conventional coupling antenna 1 comprising a substrate 10, a ground element 20, a first feed conductor 30 and a second feed conductor 40. The substrate 10 comprises a first surface 11 and a second surface 12. The ground element 20 is disposed on the second surface 12, which comprises a first portion 21, a second portion 22 and an annular groove 23. The annular groove 23 is located between the first portion 21 and the second portion 22 enclosing the first portion 21. The first feed conductor 30 is disposed on the first surface 11 corresponding to the first portion 21 and the annular groove 23. The second feed conductor 40 is disposed on the first surface 11 corresponding to the first portion 21 and the annular groove 23.
When a conventional coupling antenna 1 is utilized for transmitting wireless signal, noise is generated due to poor isolation between the first feed conductor 30 and the second feed conductor 40.